Dentifrices contain solid abrasives that remove debris and residual stains from the teeth and polish the tooth surface. The most widely used abrasives are calcium carbonate, dibasic calcium phosphate dihydrate, anhydrous dibasic calcium phosphate, tricalcium phosphate, calcium pyrophosphate, insoluble sodium metaphosphate, hydrated alumina, and hydrated silica.
Calcium carbonate, in particular, is an economical abrasive. It is found in nature in many geological forms and is generally derived from chalk, or is prepared as a precipitate from a calcium salt solution. A particularly preferred form of calcium is precipitated chalk for use in chalk-based dentifrices. So-called chalk-based dentifrices contain calcium carbonate either alone as the principal abrasive cleaning and polishing agent, or in admixture with other dental abrasives. Reference herein to chalk-based dentifrice refers to such defined dentifrices, regardless of the source or form of calcium carbonate abrasive.
An important factor in a consumer's selection of a dentifrice is its taste or flavor, so conventionally at least one or more flavoring agents are included. Among popular dentifrice flavors are wintergreen, spearmint, peppermint, cinnamon-mint, sassafras, and anise. Wintergreen is particularly popular as a principal flavor ingredient. However, the forementioned abrasive cleaning and polishing agents typically used in dentifrices generally are known absorptive materials. Consequently, they can, and frequently do, alter the organoleptic characteristics and stability of flavors owing to physical and/or chemical interactions, and selected absorption of some of the flavoring components.
In chalk-based dentifrices, the stability of wintergreen flavors especially is adversely changed. For example, it is known from experience that methyl salicylate, the main flavor component in oil of wintergreen, degrades relatively quickly in the presence of precipitated chalk leaving behind substantially no perceptable flavor. This same instability is not observed in chalk-free dentifrices. Thus, it has not heretofore been possible to use calcium carbonate in the form of precipitated chalk as an abrasive cleaning and polishing agent in dentifrice compositions flavored with wintergreen.
Thus, there is a need for a flavor-stabilizing agent for wintergreen flavoring agents containing methyl salicylate suitable for use in dentifrices containing calcium carbonate as an abrasive cleaning and polishing agent. This invention satisfies that need and provides for such a flavor-stabilizing agent.